With the rapid development of multimedia communication over wireless Internet, it is urgently needed to improve the capacity and reliability of a wireless communication system, and a conventional single-antenna transceiving communication system is challenged. The conventional technologies of transmit diversity, receive diversity or smart antenna have been inadequate to meet the requirements of a large capacity and high reliability of the new-generation wireless communication system. The above problem is solved with the appearance of a Multiple Input Multiple Output (MIMO) system. For the MIMO system, the channel capacity is increased linearly with the number of antennas, in other words, the wireless channel capacity may be increased by folds by employing MIMO channels; the spectrum utilization may be increased by folds without increasing the bandwidth and the antenna transmission power; however, the application of the MIMO system is limited due to the limited number of antennas on the terminal side. At present, based on the MIMO technology, a virtual MIMO technology has been developed to further increase the system performance. In the virtual MIMO technology, a plurality of user equipments with a small number of antennas are configured into a multi-antenna system, so that said plurality of user equipments may use the same time/frequency resources, thus the system throughput may be increased and the network Quality of Service may be improved.
A traditional Adaptive Power Control (APC) method includes that: all users are provided with preset power control thresholds; a carrier-to-interference ratio of a target signal is measured and compared with the preset threshold at the network side, and if the carrier-to interference ratio is higher than the preset threshold, a transmission power level is lowered and setting of Adaptive Modulation and Coding (AMC) is determined; otherwise, the transmitter increases the transmission power level (provided that the transmission power does not reach the maximum allowable value) and determines the setting of AMC. Thus, it can be seen that the existing power control processes are all directed to a single user equipment, and the power control of a certain user equipment takes consideration of channel conditions of said certain user equipment merely.
At present, there exists no uplink power control solution directed to the virtual MIMO system. If the traditional power control mode is employed in the virtual MIMO system, a relatively large interference may be caused between user equipments, the data transmission quality may be influenced, and system resources may be wasted.